1. Field of the Disclosure
The present disclosure relates to methods of document creation. More specifically, the present disclosure is directed to an apparatus and method for printing in which the printer's print heads are protected from substrate media contact.
2. Brief Discussion of Related Art
In certain printers using ink jet direct marking technology, it is expected that marking inks, e.g., solid inks, UV gel inks, aqueous inks and others, will be jetted directly onto cut sheet substrate media. A critical parameter in this printing process is the size of the print head to media gap. In certain current technology, the gap is set as small as 0.5 mm in order to minimize the pixel placement errors due to misdirected jets. For other print heads, for example those having high drop velocity, it is possible that the gap can be opened to 0.75-1.0 mm. Nevertheless, these tight print head to media gaps pose a challenge for any cut sheet media substrate media printer, since the sheet lead edge (LE) and trail edge (TE), and to a lesser extent the sheet body are generally not perfectly flat.
For accurate pixel placement and color registration, it is desired to keep the print head to substrate media gap within a +/−0.1 mm range about the nominal. To avoid print head front face damage, the substrate media should not be allowed to “close the gap”, i.e., to contact the print head(s). Both vacuum escort belt and/or electrostatic tack escort belt technology are technologies which may be employed to hold cut sheets of substrate media sufficiently flat. However, neither technology is completely robust against LE and TE upcurl defects.
One method of addressing the problem of upcurl defects is to provide the cut sheet printer with a pre-curler subsystem which biases sheets into a flat or down-curl configuration. However, certain initial sheet substrate media non-uniform conditions, such as corner curl, edge wave, and cockle, can be difficult to detect and fully compensate for within the precurler. Hence, sheets may not be held sufficiently flat in the print zone, to the extent that the print head(s) may be damaged.